Legitimately, not disconnects or the like lol.
For me it was this once-in-a-blue moon Priest Deck. I had just gotten a "Play 40 Spells" Quest, and so I decided I'd just jam a Priest deck entirely of Spells together and wing it.
After some ridiculous thoughtsteals, mind visions, and ressurrects -- I won the attrition war against this Druid and SMOrc'd face at the end with Mind Blasts and Holy Fires. It'll probably never come together like that again for the rest of my playing time.
How about you?